var temp=1;
function change(d) {
	if(d!=temp) {
		switch(temp) {
			case 1: a1.style.display="none"; break;
			case 2: a2.style.display="none"; break;
			case 3: a3.style.display="none"; break;
			case 4: a4.style.display="none"; break;
		}
	}
	switch (d) {
		case 1: if(a1.style.display="none")   a1.style.display="block";  else a1.style.display="none"; temp=1; break;
		case 2: if(a2.style.display="none")   a2.style.display="block";  else a2.style.display="none"; temp=2; break;
		case 3: if(a3.style.display="none")   a3.style.display="block";  else a3.style.display="none"; temp=3; break;
		case 4: if(a4.style.display="none")   a4.style.display="block";  else a4.style.display="none"; temp=4; break;
	}
}
